Simple Dart helper class to add new button elements

btn_helper.dart

class DartBtn {
  ButtonElement addButton(id, text, btnClass, container) {
    var button = new ButtonElement();
    button..id = id
          ..text = text
          ..classes.add(btnClass);
    querySelector(container).children.add(button);
    return button;
  }
}

Usage example

DartBtn btn1 = new DartBtn();
btn1.addButton(
    'alert', 
    'Display alert!', 
    'btn', 
    '#main'
)..onClick.listen((e) => window.alert('Confirmed!'));